1. Field of the Invention
The present invention relates to a vacuum pump and a heat insulating spacer used in this vacuum pump. More particularly, the present invention relates to a vacuum pump that can be used in a pressure range between low vacuum pressure and super high vacuum pressure, and a heat insulating spacer used in this vacuum pump.
2. Description of the Related Art
In manufacturing semiconductor devices such as memories and integrated circuits, a high-purity semiconductor substrate (wafer) needs to be subjected to doping and etching in a high-vacuum chamber for the purpose of avoiding the impacts of dust and the like in the air, and a vacuum pump such as a turbomolecular pump is used for evacuation of the chamber.
As this type of a vacuum pump, there has been known a vacuum pump that has a cylindrical casing, a cylindrical stator that is fixed to the inside of the casing by means of an insert, and has a thread groove portion disposed therein, a rotor supported in the stator so as to be rotatable at high speed, and heating means for keeping the temperature of the casing to a predetermined level or higher (see Japanese Patent Application Publication No. 2003-278692, for example).
In this vacuum pump, as shown in FIG. 4, the temperature of a rotor 101 and the temperature of a stator 102 surrounding the rotor 101 are increased by the heat of the rotor 101 and the heat of a drive motor, not shown, for rotating the rotor 101, and also a casing 103 is forcibly heated from the outside by means of heating means, not shown, during the operation of the vacuum pump 100, whereby the gas transferred through a thread groove portion 104 while being compressed is prevented from solidifying and depositing in the thread groove portion 104.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.